1991-2020 Degrees Fahrenheit 1 31.9 35.3 -3.4 28 48 1964 2017 1975 1974 normal 2 30.6 29.9 0.7 60 16 1984 2017 1975 1972 top-third 3 24.9 25.6 -0.7 45 31 1984 1995,1999,2015 1975 1972 normal 4 22.8 23.7 -0.9 33 41 1992 1999 1975 1972 normal 5 23.4 25.1 -1.7 25 49 1992 2018 1975 1972 normal 1966,1987,2019 6 26.5 28.2 -1.7 24 50 1992 2018 1975 1974 bottom-third 7 30.4 32.2 -1.8 22 52 1992 2018 1975 1974 bottom-third 1974 8 34.2 36.1 -1.9 22 52 1992 2018 1975 1974 bottom-third 9 37.6 39.4 -1.8 24 50 1992 2018 1975 1972 bottom-third 10 39.5 41.5 -2.0 15 59 1992 2018 1975 1974 bottom-third 1953,1958,1964,1987,1998 11 40.2 42.4 -2.2 16 58 1992 2018 1975 1974 bottom-third 12 39.9 42.5 -2.6 12 62 1984 2018 1975 1974 bottom-third 1958 18 34.7 37.7 -3.0 8 64 1993 2018 1974 1975 bottom-third 1966,1973 24 39.6 42.4 -2.8 7 65 1993 2018 1974 1975 bottom-tenth 1980 36 39.8 42.4 -2.6 6 64 1975 2018 1975 1973 bottom-tenth 48 39.4 42.2 -2.8 1 67 1976 2019 1976 1975 lowest 60 39.7 42.1 -2.4 2 64 1977 2020,2021 1976 1975 bottom-tenth